include/linux/context_tracking.h

   1 #ifndef _LINUX_CONTEXT_TRACKING_H
   2 #define _LINUX_CONTEXT_TRACKING_H
   3
   4 #include <linux/sched.h>
   5 #include <linux/percpu.h>
   6 #include <linux/vtime.h>
   7 #include <asm/ptrace.h>
   8
   9 struct context_tracking {
  10         /*
  11          * When active is false, probes are unset in order
  12          * to minimize overhead: TIF flags are cleared
  13          * and calls to user_enter/exit are ignored. This
  14          * may be further optimized using static keys.
  15          */
  16         bool active;
  17         enum ctx_state {
  18                 IN_KERNEL = 0,
  19                 IN_USER,
  20         } state;
  21 };
  22
  23 static inline void __guest_enter(void)
  24 {
  25         /*
  26          * This is running in ioctl context so we can avoid
  27          * the call to vtime_account() with its unnecessary idle check.
  28          */
  29         vtime_account_system(current);
  30         current->flags |= PF_VCPU;
  31 }
  32
  33 static inline void __guest_exit(void)
  34 {
  35         /*
  36          * This is running in ioctl context so we can avoid
  37          * the call to vtime_account() with its unnecessary idle check.
  38          */
  39         vtime_account_system(current);
  40         current->flags &= ~PF_VCPU;
  41 }
  42
  43 #ifdef CONFIG_CONTEXT_TRACKING
  44 DECLARE_PER_CPU(struct context_tracking, context_tracking);
  45
  46 static inline bool context_tracking_in_user(void)
  47 {
  48         return __this_cpu_read(context_tracking.state) == IN_USER;
  49 }
  50
  51 static inline bool context_tracking_active(void)
  52 {
  53         return __this_cpu_read(context_tracking.active);
  54 }
  55
  56 extern void user_enter(void);
  57 extern void user_exit(void);
  58
  59 extern void guest_enter(void);
  60 extern void guest_exit(void);
  61
  62 static inline enum ctx_state exception_enter(void)
  63 {
  64         enum ctx_state prev_ctx;
  65
  66         prev_ctx = this_cpu_read(context_tracking.state);
  67         user_exit();
  68
  69         return prev_ctx;
  70 }
  71
  72 static inline void exception_exit(enum ctx_state prev_ctx)
  73 {
  74         if (prev_ctx == IN_USER)
  75                 user_enter();
  76 }
  77
  78 extern void context_tracking_task_switch(struct task_struct *prev,
  79                                          struct task_struct *next);
  80 #else
  81 static inline bool context_tracking_in_user(void) { return false; }
  82 static inline void user_enter(void) { }
  83 static inline void user_exit(void) { }
  84
  85 static inline void guest_enter(void)
  86 {
  87         __guest_enter();
  88 }
  89
  90 static inline void guest_exit(void)
  91 {
  92         __guest_exit();
  93 }
  94
  95 static inline enum ctx_state exception_enter(void) { return 0; }
  96 static inline void exception_exit(enum ctx_state prev_ctx) { }
  97 static inline void context_tracking_task_switch(struct task_struct *prev,
  98                                                 struct task_struct *next) { }
  99 #endif /* !CONFIG_CONTEXT_TRACKING */
 100
 101 #endif